Annotation Type Autowired

Marks a constructor, field, setter method or config method as to be
autowired by Spring's dependency injection facilities.

Only one constructor (at max) of any given bean class may carry this
annotation, indicating the constructor to autowire when used as a Spring
bean. Such a constructor does not have to be public.

Fields are injected right after construction of a bean, before any
config methods are invoked. Such a config field does not have to be public.

Config methods may have an arbitrary name and any number of arguments;
each of those arguments will be autowired with a matching bean in the
Spring container. Bean property setter methods are effectively just
a special case of such a general config method. Such config methods
do not have to be public.

In the case of multiple argument methods, the 'required' parameter is
applicable for all arguments.

In case of a Collection or Map
dependency type, the container will autowire all beans matching the
declared value type. In case of a Map, the keys must be declared as
type String and will be resolved to the corresponding bean names.